TLEs out for three payloads and the Briz-M - nothing yet for a putative 4th payload.Briz-M in 1170 x 1504 km disposal orbit, rest in 1494 x 1506 km, so looks like mission success for the Gonets and Briz.I recall that Kosmos-2499 took a while to be discovered and cataloged.

TLEs out for three payloads and the Briz-M - nothing yet for a putative 4th payload.Briz-M in 1170 x 1504 km disposal orbit, rest in 1494 x 1506 km, so looks like mission success for the Gonets and Briz.I recall that Kosmos-2499 took a while to be discovered and cataloged.

TLEs out for three payloads and the Briz-M - nothing yet for a putative 4th payload.Briz-M in 1170 x 1504 km disposal orbit, rest in 1494 x 1506 km, so looks like mission success for the Gonets and Briz.I recall that Kosmos-2499 took a while to be discovered and cataloged.

The suspected inspector satellite Kosmos-2504 and its predecessor Kosmos-2499 (both launched piggyback with Gonets-M and Strela-3M satellites on the Rokot booster) have engines built by OKB Fakel called K50-10.6. See this list of satellites carrying engines developed by OKB Fakel :

They are the only two satellites in the list with this particular type of engine. According to the list, the satellites have an "electric engine unit (ERDU) with the K50-10.6". In this OKB Fakel leaflet (in English) the K50-10.6 is described as a thermal catalytic engine burning hydrazine:

The only other reference I can find to the the K50-10.6 thrusters is in an article about cooperation between OKB Fakel and NPO Lavochkin in the 3/2015 issue of the NPO Lavochkin magazine "Vestnik". It is mentioned in a photo caption in a section called "electric thermal catalytic hydrazine engines".

Last year there were some reports that Cosmos 2504 had performed a relatively close (~1 km) approach to a piece from the Fengyin-1 #3 destruction. Has anyone identified which piece of debris this was, please? Of course the orbital inclination difference alone would have made any encounter a brief one.

Last year there were some reports that Cosmos 2504 had performed a relatively close (~1 km) approach to a piece from the Fengyin-1 #3 destruction. Has anyone identified which piece of debris this was, please? Of course the orbital inclination difference alone would have made any encounter a brief one.

The claim was 1999-025DPP- and the closest approach I can find was 90 km at 0427 UTC Apr 21